"This has been a time of great personal and professional transition for each of us," the couple said in a joint statement. "After a great deal of thought, reflection, discussion, and prayer, we came to this decision together. At this time, we are living apart, while we work on the future of our relationship."

According to the Associated Press, Shriver recently moved out of the couple's gated estate in L.A.'s tony Brentwood neigborhood. The couple remain on speaking terms, brunching with their kids together in Santa Monica on Sunday -- and even meeting for their 25th wedding anniversary, which was April 26.

From the start, they were an unlikely couple: The daughter of Eunice Shriver (born Kennedy), former NBC journalist Shriver was the late President John F. Kennedy's niece and grew up as part America's most famous (and Democratic) political family. Schwarzenegger was an Austria-born bodybuilder who came to Hollywood and made himself into a blockbuster movie star -- before moving on to politics to become a Republican governor of California.

As their statement suggests, the duo have indeed been in the midst of major life changes: Schwarzenegger recently ended his reign as governor months ago and announced his plans to return to his old Hollywood career. Shriver, who often admitted life as California's First Lady was difficult and required sacrifice (like a break in her career as a TV journalist), mourned the January death of her father, Peace Corp founder Sargent Shriver.

Back in 2003, Shriver stood by her man's side when six women told the Los Angeles Times that the actor-turned-politician groped them inappropriately over three decades on movie sets, studio offices and elsewhere.